1. Field of the Invention
The present invention is generally concerned with printing machines of the kind in which the printing means is carried by a carriage which reciprocates on a guide.
It is more particularly directed to printing machines in which the printing means must be raised after printing an object.
This is the case with silkscreen printing machines when the objects to be printed are cylindrical, as the printing means (here a silk-screen) has to be taken out of contact with a printed object to prevent smudging the latter during return movement.
This poses the problem of raising the carriage guide carrying the silk-screen.
2. Description of the prior art
French patent No 1,263,239 corresponding to U.S. Pat. No. 3,090,300 proposes that the guide interconnect two deformable parallelograms or four-bar linkages which are controlled in an appropriate way.
French patent No 1,263,239 and U.S. Pat. No. 3,090,300 propose a printing machine comprising a frame, a guide formed by two parallel bars pivotally connected to upright arms which are part of deformable parallelograms or four-bar linkages also including cross arms pivoted to the frame. A carriage carries the printing means and reciprocates on the guide. Drive means cause the carriage to reciprocate on the guide. Lifting means cyclically rocks the upright arms carrying the guide so as to raise the printing means temporarily. The lifting means includes a cam rotatable about an axis perpendicular to the plane defined by the parallel. The edge of the cam cooperates with a cam follower roller carried by a longitudinal member controlling the deformable parallelograms.
In French patent No 1,263,239 and U.S. Pat. No. 3,090,300 the longitudinal member comprises a lever which is pivoted at one end to the frame and coupled at the other end by an arm or link of one of the deformable parallelograms.
This arrangement is satisfactory.
However, the object of the present invention is to simplify it.